MRI has been widely used by researchers to explore brain areas involved in the processing of affective stimuli (Leon-Carrion et al., 2006), near-threshold stimulus processing in the somatosensory system (Wühle et al., 2010), pitch discrimination in the auditory cortex (Brattico et al., 2009), and many other brain-behaviour studies. The conventional MRI scanner has been modified to study the functional brain. There are four main types of fMRI (functional magnetic resonance imaging)- BOLD -fMRI (Blood-Oxygen-Level-Dependent fMRI) which measures regional differences in oxygenated blood, Perfusion fMRI which measures regional cerebral blood flow, Diffusion–weight fMRI which measures random movement of water molecules, and MRI spectroscopy which measures certain cerebral metabolic activities.

Each of these types has their respective importance for psychological studies. BOLD -fMRI is based on differential magnetic properties of deoxy- and oxyhemoglobin. It has high temporal and spatial resolution. As it relies upon coupling of oxygenated blood flow and neuronal activity, it is best suitable for studying cognitive processes with rapid turning on and off property. Processes such as vision, hearing, movement, and memory belong to this category. Consequently it is not suitable for psychological processes that have slow and variable onset and also those that cannot be reversed quickly. Affective processes belong to this category.

Perfusion fMRI uses either intravenous Bolus-Tracking or arterial spin-labeling to measure cerebral blood flow. Intravenous Bolus-Tracking fMRI is based on differential regional cerebral perfusion of the magnetic compound and the coupling of blood flow and neural activities. On the other hand, in the arterial spin-labeling fMRI the hydrogen atoms are magnetically tagged through their course in the blood. It measures absolute blood flow. In Diffusion-weighted fMRI the amount of diffused water for a given pixel is calculated. This is known as Apparent Diffusion Coefficient ( ADC ). Areas with low ADC value appear more intense compared to those with high value. MRI spectroscopy identifies magnetic compounds by spectrographic peaks. It allows the study of non-water hydrogen containing molecules or molecules containing other magnetic elements.